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1.
Sci Total Environ ; 700: 134502, 2020 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-31693950

RESUMO

Organophosphate (OP) esters are emerging environmental contaminants, but little is known about their occurrence in dust. In this study, 19 OP triesters and their 11 diester degradation products were measured in indoor dust and outdoor dust collected from China. ∑OP triester concentrations in indoor dust (median: 2380 ng/g dry weight [dw]) were an order of magnitude higher than those in outdoor dust (446 ng/g dw). The median concentrations of ∑OP diesters in indoor and outdoor dust were 260 and 96.8 ng/g dw, respectively. Dust samples collected from eastern and southern China contained higher concentrations of ∑OP di- and tri-esters than those from the other regions. Dust from the most urbanized areas in China including Beijing, Shanghai, and Guangzhou exhibited the highest concentrations of ∑OP di- (>1000 ng/g dw) and triesters (>4000 ng/g dw). We also found notable concentrations of emerging aryl-OP triesters in dust (3.85-10.6 ng/g dw). Significant correlations existed between the concentrations of bis(2-ethylhexyl) phosphate (BEHP) and tris(2-ethylhexyl) phosphate (TEHP) (rho = 0.672-0.691, p < 0.01), as well as DPHP and triphenyl phosphate (TPHP) (rho = 0.537-0.766, p < 0.01) in dust samples, indicating that OP diesters originated from the degradation of triesters. High molar concentration ratios of DEP to triethyl phosphate (TEP) and DPHP to TPHP/ethylhexyl diphenyl phosphate (EHDPP) suggested that these OP triesters degrade readily. Significant correlations were found between the concentrations of ∑OP di- (R2 = 0.390, p < 0.05) and tri-esters (R2 = 0.475, p < 0.01) in paired indoor-outdoor dust samples, which suggested that indoor dust was the source of OP esters to the outdoor environment. The estimated daily intake (EDI) of ∑OP diesters through dust ingestion was 0.21 ng/kg bw/d for adults and 2.59 ng/kg bw/d for children. The exposure levels of OP diesters, DEP and DPHP, were comparable to those of their parent triester compounds.


Assuntos
Poeira/análise , Exposição Ambiental/estatística & dados numéricos , Ésteres/análise , Organofosfatos/análise , Poluição do Ar em Ambientes Fechados/análise , China , Monitoramento Ambiental , Retardadores de Chama , Humanos
2.
Food Chem ; 302: 125337, 2020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-31419770

RESUMO

The composition of volatile compounds in Korla fragrant pears was determined using headspace solid-phase microextraction followed by a gas chromatography-mass spectrometry analysis using fruits at 30, 90, and 150 days after bloom. Hexanal, (E)-2-hexenal, 1-hexanol, (E)-2-hexen-1-ol, (Z)-3-hexen-1-ol, and hexyl acetate were identified as the major compounds. The composition of volatile compounds was associated with fatty acid concentrations and key enzyme activity in the lipoxygenase pathway. In vitro linoleic and linolenic acid feeding experiments conducted using cubes of fruit flesh demonstrated that the concentrations of volatile esters, such as hexyl acetate, in the treated fruits increased significantly after incubation for 12 h compared with those in the control fruits, which was accompanied by a reduction in aldehyde and alcohol concentrations (p < 0.05 or p < 0.01). However, the treatments did not significantly influence the enzyme activity and expression of genes encoding the enzymes.


Assuntos
Frutas/química , Odorantes/análise , Pyrus/química , Pyrus/fisiologia , Compostos Orgânicos Voláteis/análise , Aldeídos/análise , Ésteres/análise , Ácidos Graxos/análise , Ácidos Graxos/metabolismo , Análise de Alimentos/métodos , Frutas/efeitos dos fármacos , Frutas/fisiologia , Cromatografia Gasosa-Espectrometria de Massas/métodos , Regulação da Expressão Gênica de Plantas , Hexanóis/análise , Ácido Linoleico/farmacologia , Pyrus/efeitos dos fármacos , Microextração em Fase Sólida/métodos , Compostos Orgânicos Voláteis/metabolismo , Ácido alfa-Linoleico/farmacologia
3.
Talanta ; 206: 120213, 2020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-31514887

RESUMO

Phthalate esters (PAEs) are an important kind of environmental endocrine disrupting chemicals, and have attracted great attention in environmental field. Present study described a new method for rapid and sensitive determination of PAEs including dibenzyl phthalate (DPhP), dibutyl phthalate (DnPP), and dicyclohexyl phthalate (DCHP) from aqueous matrices based on magnetic solid-phase extraction. Polyamidoamine (PAMAM) dendrimers-grafted magnetic-nanoparticles were synthesized and characterized, and the expected integration of more multifunctional sites of PAMAM dendrimers and rapid separation property was utilized for method development. To achieve the best extraction efficiency, several important parameters were optimized including the dosage of the adsorbent, sample pH, kind and volume of eluent, extraction time, desorption time, ionic strength. Under the optimal conditions, three phthalate esters were well enriched and simultaneously determined by high performance liquid chromatography with variable wavelength detector (VWD). Excellent linearities were observed in the range of 0.1-600 µg L-1 for DPhP and DnPP and 0.5-600 µg L-1 for DCHP, and all correlation coefficients (R2) were larger than 0.997. The limits of detection (LODs, S/N = 3) were ranged from 0.025 to 0.16 µg L-1. The spiked recoveries of PAEs in real water samples were in the range of 93.5-101.8% with satisfied relative standard deviations (RSDs) ranging from 0.9 to 4.1%. The prepared magnetic materials have shown good adsorption capability for PAEs and the developed method earned merits such as high sensitivity, simplicity, rapidness and environmental friendliness, which can be used as a robust alternative tool for monitoring PAEs in water samples.


Assuntos
Dendrímeros/química , Ésteres/análise , Nanopartículas de Magnetita/química , Ácidos Ftálicos/análise , Poluentes Químicos da Água/análise , Cromatografia Líquida de Alta Pressão/métodos , Dibutilftalato/análise , Lagos/análise , Limite de Detecção , Oceanos e Mares , Extração em Fase Sólida/métodos
4.
Food Chem ; 307: 125542, 2020 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-31639573

RESUMO

This study aimed to develop a headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC-MS) method for the quantification of 3-monochloropropane-1,2-diol fatty acid esters (3-MCPDEs) and 2-monochloropropane-1,3-diol fatty acid esters (2-MCPDEs), and semi-quantification of glycidyl fatty acid esters (GEs) in edible oils. A central composite design was implemented to optimize the derivatization temperature and extraction time, which were 100 °C and 80 min, respectively. HS-SPME coupled with in-situ derivatization was more straightforward (three steps) and sensitive, with a limit of detection of 16% (3.9 µg/L) and 11% (5.3 µg/L) higher than that of liquid injection method, for 3-MCPD and 2-MCPD, respectively. The recoveries of 3-MCPD and 2-MCPD were in the range of 91.1% to 102.1%, with a relative standard deviation ranging from 0.08 to 9.29%. The validated methodology was successfully applied to oil samples. Further efforts will focus on shortening the extraction time, as 80 min is relatively long.


Assuntos
Ésteres/análise , Cromatografia Gasosa-Espectrometria de Massas , Glicerol/análogos & derivados , Óleos Vegetais/química , Microextração em Fase Sólida/métodos , alfa-Cloridrina/química , Ésteres/química , Ácidos Graxos/química , Contaminação de Alimentos/análise , Glicerol/química , Limite de Detecção
5.
Food Chem ; 306: 125623, 2020 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-31606633

RESUMO

In this study, apple juice was fermented using Hanseniaspora osmophila X25-5 in pure culture as well as mixed culture with Torulaspora quercuum X24-4, which was inoculated simultaneously or sequentially. H. osmophila inhibited the growth of T. quercuum, while T. quercuum had little effect on the growth of H. osmophila. The simultaneous fermentation consumed relatively more sugar and resulted in the highest ethanol content. The production of organic acids varied depending on the yeast species employed and inoculation modality. Esters and alcohols were the main volatile families produced during fermentation, while ethyl esters and terpenes contributed most to the temperate fruity aroma. Gas chromatography-olfactometry (GC-O) showed that 3-methyl-1-butanol, ethyl 2-methylbutanoate, phenylethyl alcohol, ß-phenethyl acetate, and ß-damascenone were the most potent odorants in all samples. This study suggested that simultaneous fermentation with H. osmophila and T. quercuum might represent a novel strategy for the future production of cider.


Assuntos
Acetatos/análise , Fermentação , Hanseniaspora/metabolismo , Malus/metabolismo , Odorantes/análise , Torulaspora/metabolismo , Bebidas Alcoólicas , Cromatografia Gasosa , Ésteres/análise , Frutas/química , Norisoprenoides/análise , Olfatometria , Vinho/análise
6.
Food Chem ; 308: 125555, 2020 Mar 05.
Artigo em Inglês | MEDLINE | ID: mdl-31655483

RESUMO

Saccharomyces cerevisiae flor yeast is used for the first time in sparkling wine-making. Twenty-six oenological variables and fifty-three volatile metabolites are quantified in the middle (P = 3 bar) and at the end (P = 6 bar) of the second fermentation, carried out in open and closed bottles. A heat-map of volatiles and the fingerprints obtained for ten chemical families and ten odorant series visualize the changes for each condition. Terpenes, fatty acids and volatile phenols increased their contents by pressure effect at the end of the study by 25.0, 7.8 and 2.2%, respectively. The remaining families decrease between 17.4% and 30.1% for furanic compounds and esters in the same stage. A Principal Component Analysis established that nine volatiles are mainly affected by pressure and five by fermentation stage. The use of ethanol-tolerant flor yeasts constitutes an innovative procedure for the enhancement of the sparkling wines diversification.


Assuntos
Dióxido de Carbono/química , Fermentação , Saccharomyces cerevisiae/metabolismo , Vinho/análise , Dióxido de Carbono/análise , Ésteres/análise , Odorantes/análise , Pressão
7.
Huan Jing Ke Xue ; 41(1): 205-212, 2020 Jan 08.
Artigo em Chinês | MEDLINE | ID: mdl-31854921

RESUMO

We explored the pollution characteristics, spatial and temporal distribution, ecological risk, and human health risk of organophosphate esters (OPEs) in the source water of the Nanjing section of the Yangtze River. Thirteen OPEs were determined by solid phase extraction-high performance liquid chromatography-tandem mass spectrometry. The results showed that twelve OPEs were detected to different extents with total concentrations ranging from 85.21 to 1557.96 ng·L-1[excluding tris (2,3-dibromopropyl) phosphate]. Chloroalkyl phosphate was the main compound and tris(2-chloroethyl) phosphate (TCEP) was the most abundant of the thirteen OPEs, which reached up to 447.08 ng·L-1. Seasonal variation of OPEs showed that the concentrations of OPEs in summer ranged from 220-1557.96 ng·L-1, with the average concentration of 493.78 ng·L-1 being 1.7-2.6 times higher than of that in spring and autumn. An ecological risk assessment showed that tricresyl phosphate and 2-ethylhexyl diphenyl phosphate were associated with moderate or high risks to organisms (algae, crustaceans, and fish). At a high exposure concentration, the total non-carcinogenic risk of OPEs in source water ranged from 4.41×10-3-2.91×10-2, with the highest risk being associated with children aged 0-3 months. The total cancer risk value was 5.88×10-7-3.89×10-6, among which TCEP and Tris(1,3-dichloro-2-propyl) phosphate was associated with a potential risk for children. We conclude that the long-term exposure risk for children of OPEs in the source water of the Nanjing section of the Yangtze River deserve more attention.


Assuntos
Monitoramento Ambiental , Retardadores de Chama/análise , Organofosfatos/análise , Rios/química , Poluentes Químicos da Água/análise , Animais , China , Ésteres/análise , Humanos , Lactente , Recém-Nascido , Medição de Risco , Estações do Ano
8.
Huan Jing Ke Xue ; 41(1): 232-241, 2020 Jan 08.
Artigo em Chinês | MEDLINE | ID: mdl-31854924

RESUMO

This study assesses the spatial distribution characteristics and ecological risk of phthalate esters (PAEs) in the surface sediments of the mainstream and tributaries of the Songhua River, China, using concentrations and composition of six PAEs, which were analyzed using gas chromatography-mass spectrometery (GC-MS). We assess the ∑6PAEs ecological risk using the hazard quotient (HQ) method and environmental risk levels (ERL). The results were as follows. ① It was found that the total concentrations of ∑6PAEs ranged from 6832.5 to 36298.9 ng·g-1 dry weight (average 18388.6 ng·g-1), with the main contributions coming from di-(2-ethylhexyl) phthalate (DEHP) and di-n-butyl phthalate (DBP). The difference between the main stream ∑6PAEs (6832.5-36298.9 ng·g-1, average 18616.9 ng·g-1) and the tributary ∑6PAEs (10367.6-26593.3 ng·g-1, average 18264.1 ng·g-1) was not significant (P >0.05). The mean concentrations of individual PAEs in the tributary stream differed little from that of the main stream. The ∑6PAEs concentration of the Songhua River decreased initially but then increased from the upstream to the downstream. The average ∑6PAEs concentration in natural agricultural areas (18677.5 ng·g-1) was similar to that found in urban industrial areas (18063.7 ng·g-1), and DBP and DEHP contributed 98% of ∑6PAEs. ② The main sources of ∑6PAEs were domestic, agricultural production, and industrial production using plasticizers. ③ The ecological risk assessment indicated that DMP and BBP in the surface sediments of the Songhua River did not pose an ecological risk for aquatic organisms, and that DEP was associated with a low ecological risk, whereas DEHP and DBP posed a high ecological risk for aquatic organisms.


Assuntos
Ésteres/análise , Sedimentos Geológicos/química , Ácidos Ftálicos/análise , Rios/química , Poluentes Químicos da Água/análise , China , Dibutilftalato , Medição de Risco
9.
Food Chem ; 307: 125553, 2020 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-31654952

RESUMO

Aroma contribution of individual esters has been studied in complex mixtures mimicking red wine models. A mixture containing 14 ethyl esters at concentrations found in wine (V1) was prepared and kept as reference. Isointense and qualitatively similar aroma vectors with a reduced number of esters (V2-V7) were prepared. Those vectors were introduced in two reconstituted wines to assess whether simpler vectors could replace V1 without compromising wine quality. In the simpler young wine model, V1 could be replaced by a vector containing just 3 odorants (ethyl 2-methylbutyrate, ethyl butyrate and hexanoate). In the oaky model, a vector containing just ethyl 2-methylbutyrate (V7) could replace V1 without any discernible sensory change. Results also reveal that sub- or perithreshold odorants play outstanding roles on the overall odour intensity of the mixture and that aroma simplification concomitantly implies an increase in the amount of odorant required to keep the intensity of the aroma vector.


Assuntos
Ésteres/análise , Odorantes/análise , Vinho/análise
10.
Environ Pollut ; 255(Pt 2): 113332, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31606663

RESUMO

Organophosphate esters (OPEs) in indoor dust were closely related to human health. However, OPE contamination in college library dust remained unknown at present. In this study, OPEs were first investigated in 78 indoor dust samples and 26 field blanks of 26 college libraries from 13 prefecture-level cities across China between October and December 2017. The total OPEs fell in the range of 8706-34872 ng/g, and were dominated by tris(2-chloroisopropyl) phosphate (TCIPP), tris(2-chloroethyl) phosphate (TCEP) and tris(2-butoxyethyl) phosphate (TBOEP). OPEs exhibited geography-specific distributions, with high levels in Beijing, Shanghai and Guangzhou. OPEs significantly correlated with population density and gross domestic product (p < 0.01), indicating the distinct effect of these two indicators on OPE pollution. Analysis of pollution source indicated volatilization and abrasion as main emission pathways of OPEs from OPEs-added products to dust. The daily exposure doses (DEDs) of OPEs via dust ingestion, inhalation and dermal contact were similar for male and female students, ranging from 1.35 to 5.92 ng/kg-bw/day during study time in libraries (25% of day). High DEDs were found in Beijing, shanghai and Guangzhou, indicating high exposure risk of OPEs to college students in large cities. The non-carcinogenic and carcinogenic risks of OPEs to college students were quantitatively evaluated based on the oral reference dose and cancer slope factor of OPEs recently updated by USEPA, and all much lower than the threshold risk values. However, the potential risk may occur if exposure to OPEs is high in other microenvironments over remaining hours of the day.


Assuntos
Poeira/análise , Exposição Ambiental/análise , Organofosfatos/análise , Universidades , Pequim , China , Cidades , Exposição Ambiental/estatística & dados numéricos , Monitoramento Ambiental , Ésteres/análise , Feminino , Retardadores de Chama/análise , Humanos , Estados Unidos , United States Environmental Protection Agency
11.
Environ Sci Pollut Res Int ; 26(30): 31301-31314, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31471852

RESUMO

Non-edible seeds are not used in any commercial applications, which implies that they can be used for biofuel applications. The present study aimed to maximise the process conditions for oil extraction and sterculia biodiesel production from Sterculia foetida (poon oil). GC-MS identified the methyl esters of sterculia oil as sterculic acid (32%), palmitic acid (15.88%), oleic acid (10.00%), linoleic acid (9.95%) and malvalic acid (9%). Response surface methodology (RSM) based parametric optimisation of oil extraction was carried out by choosing process variables such as sample weight, volume of solvent to seed ratio and time. The optimum sample amount of 7.5 g and the volume of solvent to seed ratio of 40 mL/g resulted in a maximum oil yield of 45.27% at 3 h. The results were statistically significant (P < 0.05) with a regression coefficient (R2) of 0.9988. Furthermore, the artificial neural network (ANN) resulted in an R2 value greater than 0.9, which validates the RSM. Conventional optimisation of the temperature (55 °C), feedstock to methanol ratio (1:12), catalyst proportion (1.5%) and transesterification reaction time (60 min) yield 90.87% biodiesel production. The physicochemical characteristics of oil and biodiesel complied with the requirements of the ASTM standards. The rate constant and thermodynamic variables at the optimum temperature (333 K) were calculated from the experimental data. The activation energy (Ea), activation enthalpy in transition state theory (ΔH++), activation entropy in transition state theory (ΔS++) and Gibbs free energy in transition state theory (ΔG++) were 37.91 kJ mol-1, 35.14 kJ mol-1, - 239.58 J mol-1 K-1 and 79.81 kJ mol-1 respectively. Graphical abstract.


Assuntos
Biocombustíveis , Fracionamento Químico/métodos , Óleos Vegetais/isolamento & purificação , Sementes/química , Sterculia/química , Catálise , Esterificação , Ésteres/análise , Metanol , Óleos Vegetais/análise , Óleos Vegetais/química , Temperatura Ambiente , Termodinâmica
12.
Environ Monit Assess ; 191(10): 627, 2019 Sep 09.
Artigo em Inglês | MEDLINE | ID: mdl-31501942

RESUMO

In this work, we investigated possible contamination of phthalates in seawater and sediment around the eastern coast of Thailand in the area of Chonburi, Rayong, and Chanthaburi. The main focus was on Pradu Bay east of Map Ta Phut, a well-known industrial and economic hub in Thailand. Among six selected phthalates of interest, diethyl phthalate (DEP), and benzyl butyl phthalate (BBP) were not found in any sample, while the concentrations of dimethyl phthalate (DMP) and dioctyl phthalate (DnOP) were very low or undetectable in most samples. In December 2014, the concentration of dibutyl phthalate (DBP) and diethylhexyl phthalate (DEHP) in Pradu Bay were 0.23-0.77 and 0.31-0.91 µg L-1 in seawater, respectively and non-detected (ND)-0.80 and ND-1.65 µg g-1 for 11 out of 20 sediment samples. DBP and DEHP were considered as the predominant congeners. A surface mapping system provided us an overview concentration distribution of DBP and DEHP congeners in seawater and sediment in Pradu Bay, showing a correlation between water and sediment and allowing a prediction of a possible point source. A comparison with the EU standard concentration limit in surface water confirmed that the phthalate concentration in this area was acceptable. However, continuous monitoring of phthalate congeners in the matrices should be done to detect a possible increase in their concentrations. To the best of our knowledge, this is the first study to determine concentrations of phthalates in seawater and sediment along the east coast of Thailand.


Assuntos
Sedimentos Geológicos/química , Ácidos Ftálicos/análise , Água do Mar/química , Dibutilftalato/análise , Dietilexilftalato/análise , Monitoramento Ambiental , Ésteres/análise , Tailândia
13.
Anal Bioanal Chem ; 411(27): 7147-7156, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31492999

RESUMO

Ester and amide derivatives of hydroxycinnamic acids are found in black cohosh (Actaea racemosa) and other Actaea plants. These two compound groups were evaluated for authentication of black cohosh dietary supplements. The hydroxycinnamic acid esters (HCAE) were profiled by ultra-performance liquid chromatography-photodiode array detection (UPLC-PDA). The hydroxycinnamic acid amides (HCAA) were acquired simultaneously by mass spectrometry-multiple reaction monitoring (UPLC-MRM) mode. In contrast with the traditional HCAE method using 8 compounds, profiles of HCAA using only 4 feruloyl dopamine-O-hexosides was more convenient for peak by peak comparison. Partial least square discriminant analysis (PLS-DA) was applied to both HCAE and HCAA datasets. Authenticated plant samples of five Actaea species were randomly divided into training and test sets to build and validate the two PLS-DA models. Both models provided reasonable estimates for the classification of A. racemosa and other Actaea plant samples. However, HCAA model performs better in sensitivity, specificity, and accuracy. Assessment of supplement samples provided quite different results for the solid and liquid dietary supplement samples, indicating the dosage form could affect the composition of marker compounds. Graphical abstract.


Assuntos
Actaea/química , Ácidos Cumáricos/química , Suplementos Nutricionais/análise , Amidas/análise , Cromatografia Líquida/métodos , Contaminação de Medicamentos , Ésteres/análise , Limite de Detecção , Espectrometria de Massas/métodos , Espectrofotometria Ultravioleta
14.
Ecotoxicol Environ Saf ; 184: 109563, 2019 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-31473562

RESUMO

A rapid and simple method based on liquid chromatography-tandem mass spectrometry (LC-MS/MS) of sample preparation using QuEChERS was developed for detecting residues of QYR301, a new HPPD-inhibiting herbicide, in rice plant (straw), water, soil, rice hull and brown rice (BR). To eliminate matrix interference, matrix-matched calibrations with satisfactory linearity (R2 > 0.99) were used for accurate quantification. The method showed recoveries of 90.3-108.1% and relative standard deviations (RSDs) < 11%. The limits of quantification (LOQ) for QYR301 were 0.005 mg kg-1 in all five matrixes. Furthermore, the dissipation kinetics and terminal residues of QYR301 were determined at two sites in 2018. The days for 50% dissipation (DT50) of QYR301 in rice plants, water and soil were 3.6-4.4, 0.7-3.0 and 4.3-8.0 d, respectively, which indicated that QYR301 is a short-persistence herbicide. Moreover, no QYR301 residues were detected in BR, rice hull and straw collected at harvest following its application at 1.0 or 1.5 × of the recommended high rate. These results will help organizations and governments establish related principles/laws regarding the use of QYR301 in terms of environmental protection, food safety and other potential aspects.


Assuntos
Monitoramento Ambiental/métodos , Ésteres/análise , Herbicidas/análise , Oryza/química , Pirazóis/análise , Poluentes do Solo/análise , Poluentes Químicos da Água/análise , Cromatografia Líquida , Meia-Vida , Cinética , Espectrometria de Massas em Tandem
15.
J Chromatogr A ; 1607: 460392, 2019 Dec 06.
Artigo em Inglês | MEDLINE | ID: mdl-31371201

RESUMO

Approaches to simulate peak time and intensity profiles of compounds in comprehensive two dimensional gas chromatography (GC × GC) were developed, and which are demonstrated for separation of a mixture of saturated and unsaturated fatty acid methyl esters (FAME) using a range of column sets. The simulation of first and second dimension time (1tR and 2tR) of FAME relies on use of a Gibbs energy additivity approach to correlate with the structures of FAME. First and second dimension peak standard deviations (1σ and 2σ) of the compounds were further calculated from the 1tR and 2tR data according to the plate height concept which provided good agreement between the predicted and experimental peak widths at half height in one dimension GC (1DGC) with an overall R2 of 0.9628. The effect of 1σ distortion caused by the modulation process was also taken into account in the peak width simulation where the simulated 1σ data were rounded up to multiples of the scale of modulation period (PM). Two dimension Gaussian equations were then used to generate GC × GC results (2D contour plots) from simulated 1tR, 2tR, 1σ and 2σ data for FAME separation on different column sets employing ionic liquid and conventional columns. Good overall correlations between experimental and simulated 1tR and 2tR were obtained with R2 of 0.9951 and 0.9802, respectively, and the simulated 2D contour plots were an acceptable match with the experimental results.


Assuntos
Cromatografia Gasosa/métodos , Simulação por Computador , Algoritmos , Ésteres/análise , Ácidos Graxos/análise , Líquidos Iônicos/química , Íons , Termodinâmica , Fatores de Tempo
16.
Sci Total Environ ; 695: 133894, 2019 Dec 10.
Artigo em Inglês | MEDLINE | ID: mdl-31425989

RESUMO

Ten urinary biomarkers of organophosphate esters (OPEs) from six parent OPEs were analyzed in urine from adolescents students in Eastern China. Bis (1,3-dichloro-2-propyl) phosphate, urinary biomarker of tris (1,3-dichloro-2-propyl) phosphate (TDCIPP), was detected in all urine samples with the highest residual concentration of 6.2 ng/mL (median). Bis (1-chloro-propyl) hydroxyl-2-propyl phosphate, dibutyl phosphate, biomarkers of tris (1-chloro-2-propyl) phosphate (TCIPP), tri-n-butyl phosphate (TNBP), respectively, and tris (2-chloroethyl) phosphate (TCEP), were also frequently detected with median concentrations of 1.5, 2.6 and 0.3 ng/mL, respectively. Results indicate that exposure to OPEs, in particular to TDCIPP, TNBP, TCIPP and TCEP, was highly prevalent for adolescent students. The exposure pathways of OPEs were then evaluated according to the OPE internal body burdens (IBBs). Three pathways were identified as the main pathways for adolescents exposed to OPEs including dermal absorption, oral intake of food and dust and inhalation.


Assuntos
Exposição Ambiental/estatística & dados numéricos , Poluentes Ambientais/urina , Organofosfatos/urina , Adolescente , China , Monitoramento Ambiental , Ésteres/análise , Ésteres/urina , Humanos
17.
Artigo em Inglês | MEDLINE | ID: mdl-31437078

RESUMO

This study was conducted to investigate on the effect of different sampling regions of palm-refined oils and fats on the 2- and 3-monochloropropanediol fatty acid esters (MCPDE) and glycidol fatty acid esters (GE) levels. The American Oil Chemists' Society (AOCS) Official Method Cd 29a-13 on the determination of MCPDE and GE in edible oils and fats by acid transesterification was successfully verified and optimised, with slight modification using 7890A Agilent GC system equipped with 5975C quadrupole detector. The determined limits of detection (LOD) for MCPDE were 0.02 mg kg-1 and 0.05 mg kg-1 for GE. The method performance has showed good recovery between 80% and 120% for all pertinent compounds with seven replicates assayed in three separate days. Round robin test with two European laboratories, i.e. Eurofins and SGS, has shown compliance results with those of the present study. Among the sampling regions, only one refinery located in the central region of Malaysia showed a significant increment of the MCPDE and GE levels after refining process. The GE level averaging at 2.5 mg kg-1 was slightly higher than that of 3-MCPDE averaging at 1.3 mg kg-1. Both esters were preferentially partitioned into the liquid phase rather than the solid phase after fractionation. However, the overall results exhibited no direct correlation between the esters content and the different sampling locations of the palm oil products in Malaysia. Analysis of total chlorine content also displayed significant variations between sampling locations which clearly show its effect on the chlorine content in the CPO samples.


Assuntos
Compostos de Epóxi/análise , Ésteres/análise , Contaminação de Alimentos/análise , Glicerol/análogos & derivados , Óleo de Palmeira/química , Propanóis/análise , alfa-Cloridrina/análise , Ácidos Graxos/análise , Análise de Alimentos , Glicerol/análise , Malásia , Reprodutibilidade dos Testes
18.
Molecules ; 24(17)2019 Aug 27.
Artigo em Inglês | MEDLINE | ID: mdl-31461894

RESUMO

Doubanjiang, a Chinese traditional fermented red pepper paste, is eaten worldwide for its unique flavor. The objective of this study was to evaluate the aroma quality of doubanjiang using solvent-assisted flavor evaporation (SAFE) and headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography-olfactometry (GC-O) and aroma extract dilution analysis (AEDA). A total of 165 volatile compounds, belonging to 13 chemical classes, were identified. Esters and hydrocarbons were the predominant groups. Thirteen aroma-active compounds were detected by AEDA of SAFE and HS-SPME, and their odor activity values (OAVs) were calculated by dividing their concentration by their odor threshold in water. Among them, ethyl isovalerate, ß-damascenone, 3-isobutyl-2-methoxypyrazine (IBMP), and sotolone had the highest OAVs (>1000). In addition, sotolone, methional, ß-damascenone, 3-isobutyl-2-methoxypyrazine, ethyl isovalerate, phenylethyl alcohol and linalool had high flavor dilution (FD) factors. Sotolone, ß-damascenone and 3-isobutyl-2-methoxypyrazine were identified for the first time in doubanjiang and played significant roles in its aroma quality.


Assuntos
Capsicum/química , Odorantes/análise , Compostos Orgânicos Voláteis/análise , Cromatografia Gasosa , Ésteres/análise , Fermentação , Hidrocarbonetos/análise , Extratos Vegetais/análise , Microextração em Fase Sólida
19.
J Chromatogr A ; 1605: 460364, 2019 Nov 08.
Artigo em Inglês | MEDLINE | ID: mdl-31320132

RESUMO

In this work, magnetic Ni doped nanoporous carbon (Ni-C) microspheres were prepared by directly calcinating Ni based metal-organic framework at 400 °C in nitrogen. The morphology and surface area of Ni-C microspheres were characterized by electron microscopy and N2 adsorption-desorption isotherms. The results demonstrated that Ni nanoparticles were wrapped by the carbon matrix, resulting in the Ni-C microspheres with a strong magnetic response. The Ni-C microspheres also showed high surface area and micro/meso-porous structure, which make them efficient and recyclable magnetic adsorbent. The Ni-C microspheres were employed for magnetic solid phase extraction of phthalate esters from juice and water samples before high performance liquid chromatographic analysis. The limits of detection (S/N = 3) of the method were 0.2-0.3 ng mL-1 for juice sample and 0.02-0.03 ng mL-1 for water sample. The recoveries of all analytes were between 90.0%-100.6%. The Ni-C microspheres showed a great deal of potential to be an adsorbent for enrichment of other organic pollutants in different samples.


Assuntos
Carbono/química , Ésteres/análise , Fenômenos Magnéticos , Estruturas Metalorgânicas/química , Microesferas , Nanoporos , Níquel/química , Ácidos Ftálicos/análise , Adsorção , Bebidas/análise , Concentração de Íons de Hidrogênio , Nanoporos/ultraestrutura , Nitrogênio/química , Porosidade , Soluções , Solventes , Água/química , Poluentes Químicos da Água/análise , Difração de Raios X
20.
J Chromatogr A ; 1603: 199-207, 2019 Oct 11.
Artigo em Inglês | MEDLINE | ID: mdl-31262516

RESUMO

Aryl organophosphate esters (aryl-OPEs) have gained increasing interest over the past few years since a growing number of emerging aryl-OPEs were identified in the environmental media. The currently available analytical methods for aryl-OPEs are usually tailored to detect a very limited number of aryl-OPEs and have inadequate sensitivity for several emerging aryl-OPEs. In this work, a comprehensive and sensitive method for the quantitative analysis of 17 aryl-OPEs in indoor dust samples by liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed and validated. The method allows for the determination of four traditional and thirteen emerging aryl-OPEs, which compose almost all the environmentally relevant aryl-OPEs that have been identified. For the first time, 2-isopropylphenyl diphenyl phosphate (2IPPDPP), 2,4-diisopropylphenyl diphenyl phosphate (24DIPPDPP), bis(2-isopropylphenyl) phenyl phosphate (B2IPPPP), bis(4-tert-butylphenyl) phenyl phosphate (B4tBPPP), and 2-naphthalenyl phosphate (NDPHP) were analyzed using LC-MS/MS. With a systematic optimization of the MS/MS parameters, chromatographic separation conditions, and sample preparation procedures, the target aryl-OPEs in the indoor dust were well separated within 13 min in one analytical run, with limits of quantification ranging from 0.09 to 3.2 ng g-1. Compared with the previously published methods, this method obtained a better sensitivity for most aryl-OPEs. The validated method was applied to 12 indoor dust samples that were collected from residential houses in Guangzhou, China. Both the traditional and emerging aryl-OPEs were frequently detected in the samples, except for NDPHP, with ∑aryl-OPEs ranging from 90 to 33,800 ng g-1. In particular, elevated concentrations of the newly identified tris(2,4-di-tert-butylphenyl) phosphate (AO168 = O) were observed in all the indoor dust samples. To our knowledge, these are the first reported data of AO168 = O levels in the environment media from China. These data indicate that AO168 = O is a ubiquitous pollutant that was previously overlooked and merits further investigation in the environment.


Assuntos
Poluição do Ar em Ambientes Fechados/análise , Cromatografia Líquida/métodos , Poeira/análise , Ésteres/análise , Organofosfatos/análise , Espectrometria de Massas em Tandem/métodos , Calibragem , China , Solventes
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